1. Field of the Invention
The present invention relates to an optical disc controller and an optical disc drive system, and in particular, to an optical disc controller and an optical disc drive system used for an optical disc in which data is recorded while being divided into data capacity units to which error correction code can be added.
2. Description of the Background Art
In a personal computer (hereinafter, also referred to as PC) or DVD recorder (hereinafter, also referred to as recorder), file data and moving image data is sometimes recorded in Blu-ray disc, DVD-RAM disc or the like using an optical disc drive. In such a case, file data or moving image data sent from the PC or recorder is recorded into the Blu-ray disc, DVD-RAM disc or the like while being divided into units of data capacity for which error correction code can be added in accordance with physical specification of the particular disc.
Here, data that is recorded into a Blu-ray disc, DVD-RAM disc or the like is treated in units of sectors each consisting of 2 KB. And a data capacity unit to which error correction code can be added in accordance with physical specification of each disc is 32 KB corresponding to 16 sectors in the case of DVD-RAM and 64 KB corresponding to 32 sectors in the case of Blu-ray.
Usually, recording instruction from a PC or a recorder to an optical disc drive is made by ATAPI (AT Attachment Packet Interface) command. In this ATAPI command, instruction is made by a logical address in which recording start position increases by a unit of one sector from zero, and a recording data capacity represented by a number of sectors. In an optical disc, this logical address is converted to a physical address on medium and used as a recording start position.
In this case, the converted physical address representing recording start position is not necessarily situated at a boundary of 32 KB in the case of DVD-RAM or at a boundary of 64 KB in the case of Blu-ray, but is generally in the middle of data capacity unit of 32 KB or 64 KB. Likewise, a physical address representing recording end position is generally in the middle of data capacity unit of 32 KB or 64 KB. In such a case, data is not written into the entire data capacity unit to which error correction code can be added in accordance with physical specification, so that there is deficient data.
According to a physical specification of a particular disc such as DVD-RAM or Blu-ray, when data deficiency occurs in writing to an optical disc, the deficient data is supplemented in a unit of sector using data on the optical disc or “0” data. Concretely, a physical specification defines that the deficiency is supplemented by data on the optical disc when data is already recorded in the same physical address for the deficient data on the optical disc, while the deficiency is supplemented by “0” data when data is not recorded on the optical disc.
As described above, in an optical disc drive, data is read out from boundary of 32 KB or 64 KB including a physical address of recording start position so as to supplement data, and the read out data is copied to the data that is deficient at the time of writing each sector. This series of processes is called “recording data merge process”.
The process concerning an optical disc drive is described, for example, in Japanese Patent Application Laid-Open No. 2004-199740 and Japanese Patent Application Laid-Open No. 2002-319137.
However, occurrence of recording data merge process in an optical disc drive caused deterioration in recording performance compared to the case where recording data merge process does not occur. Concretely, the recording data merge process increases the processing time for reading out deficient data from the optical disc and the processing time for hardware and software that copies and transfers the read out data to a specific buffer. Therefore, processing time of hardware and software increases in the case where recording data merge process occurs, compared to the case where recording data merge process does not occur, leading deterioration in recording performance in the optical disc drive. However, in recording data merge process, the processing time for reading out data from the optical disc so as to supplement deficient data is essential for satisfying the physical specification.